Compojure/Ring: can't get session working

Question

I'm clearly missing something obvious, but:

(ns session-demo.core
  (:gen-class)
  (:use compojure.core
        ring.middleware.session
        [hiccup core page form])
  (:require [compojure.route :as route]
            [compojure.handler :as handler]))

(defn index-page []
    (html5
     [:body
      (form-to [:get "/status"]
               (submit-button "Proceed"))]))

(defn status-page [params]
  (html5
   [:body
    [:p "Session: " (:session params)]
    [:p "Params: " params]]))

(defroutes the-routes
  (GET "/" [] (index-page))
  (GET "/status" {session :session :as params} (status-page params)))

(def app
  (-> (handler/site the-routes)
      wrap-session))

After clicking "Proceed" button shows:

Session: {}

Params: {:ssl-client-cert nil, :remote-addr "127.0.0.1", :scheme :http, :query-params {}, :session {}, :form-params {}, :multipart-params {}, :request-method :get, :query-string nil, :route-params {}, :content-type nil, :cookies {"org.cups.sid" {:value "72d6fc6a299669e6332da6eb72964f97"}}, :uri "/status", :server-name "localhost", :params {}, :headers {"accept-encoding" "gzip, deflate", "user-agent" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:28.0) Gecko/20100101 Firefox/28.0", "referer" "http://localhost:3000/", "connection" "keep-alive", "accept-language" "en-US,en;q=0.5", "accept" "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", "host" "localhost:3000", "cookie" "org.cups.sid=72d6fc6a299669e6332da6eb72964f97"}, :content-length nil, :server-port 3000, :character-encoding nil, :body #, :flash nil}

I'd expect something meaningful to be set in (:session params)...

Answer 1

The session starts empty. To put something in the session you need to return a map from your handler, and under the key :session you should provide the updated session data.

Something like this maybe:

(defn index-page []
  {:body (html5
          [:body
           (form-to [:get "/status"]
                    (submit-button "Proceed"))])
   :session {:test [1 2 3]}})